The present invention generally pertains to electronic direction finding systems and methods and is specifically directed to determining the direction of arrival of a received signal.
A prior art direction finding system for determining the direction of arrival at a particular location of signals received by a plurality of antennas that are arrayed in a known pattern in relation to the particular location is described in U.S. Pat. No. 6,384,784 B1. This prior art system includes an array of antennas in a predetermined configuration for receiving a signal from a modulated, or interfering, signal source. The individual outputs from each antenna are input to respective direct sequence spread spectrum modulators where each is multiplied by a unique pseudo-random number code, unique either in value or in time relationship. The spread spectrum outputs are summed and the summed output is demodulated and digitized to produce a digitized intermediate frequency (IF) signal. The digitized IF signal is processed by a digital signal processor to determine the relative phase or time of arrival of the signal from the modulated signal source at each antenna relative to one of the antennas used as a reference. The relative phases or times of arrival and the predetermined configuration of the antenna array are then used to estimate the direction of arrival from the modulated signal source.